Aerosols are gaseous suspensions of fine solid or liquid particles that are useful in a wide variety of applications. For example, medicated liquids may be administered in aerosol form. Medicated aerosols include materials that are useful in the treatment of respiratory ailments. In such applications, the aerosols may be produced by an aerosol generator and inhaled into a patient's lungs. Aerosols are also used in non-medicinal applications including, for example, industrial applications.
Aerosol generators are known that include a heated tube for vaporizing liquid. For example, commonly-assigned U.S. Pat. No. 5,743,251, which is incorporated herein by reference in its entirety, discloses an aerosol generator including a tube and a heater operable to heat the tube to a sufficient temperature to volatilize liquid in the tube. It is disclosed that the volatilized material expands out of an end of the tube and admixes with ambient air, thereby forming an aerosol.
As shown in FIG. 1, the aerosol generator 21 disclosed in the '251 patent includes a tube 23 defining a capillary-sized fluid passage and having an open end 25. The tube 23 also includes an inlet end 31 in fluid communication with a source 33 of liquid material. A heater 27 is positioned adjacent to the tube 23. The heater 27 is connected to a power supply 29. In operation, liquid is introduced into the tube 23. The heater 27 heats a portion of the tube 23 to a sufficiently high temperature to volatilize the liquid. The volatilized material expands out of the open end 25 of the tube and admixes with ambient air. When it is desired to generate an aerosol for drug inhalation, the aerosol generator 23 is preferably provided with a puff-actuated sensor 37 (shown by dotted lines), which preferably forms part of a mouthpiece 39 (shown by dotted lines) disposed proximate the open end 25 of the tube 23.
Other aerosol generators including a heated tube for vaporizing liquids to produce an aerosol are described in commonly-assigned U.S. Pat. Nos. 6,234,167 and 6,568,390 and commonly-assigned U.S. patent application Ser. No. 10/003,437 filed Dec. 6, 2001, each incorporated herein by reference in its entirety.